Means and method of processing canned foods



Dec. 5, 1939. o. w. LANG :1- AL MEANS AND METHOD OF PROCESSING CANNEDFOODS Filed Sept. 28, 1936 2 Sheets-Sheet 1 CONDUC TING FLU/D s 1 m m HE v. W m r Z XM A 2 5 Q g a L 00 c T A W OH 2 u B M 7 7 2 Dec. 5, 1939.1 o. w. LANG El" AL 1 2,182,333

MEANS AND METHOD OF PROCESSING CANNED FOODS Filed Sept. 28, 1936 2Sheets-Sheet 2 INVENTORST OTTO W. LANG HAROLD C. EETTS BY Mfl W FATTORNEYS.

Patented Dec. 5, 1939 MEANS AND METHOD or raocnssmo omen roons Otto W.Lang and Harold C. Betta; San Francisco, Calif.; said Betta assignor offifteen per cent tosaidLang Application September 2a, 1936, Serial No.102,855

3Claims;

Our invention relates to a means and method for processing materialsdesigned to be packed and sold in metal containers, and moreparticularly to a means and method for pre-heating,

I pasteurizing or cooking foods packed and sold in tin plate containerscommonly known as cans.

Among the objects of our invention are; -To provide a fast andeconomical method of heating food in cans during packing; to provide asimple 10 method of preheating, pasteurizing or cooking food stuitswhile being canned; to provide a means and method for heating cannedfood during processing so as to greatly reduce the space required in theprocessing plant; and to provide a simple and eifective means and methodfor electrically cooking canned foods, or other organic materials, wetor dry.

Our invention possesses numerous other obiects and features ofadvantage, some of which,=

together with the foregoing, will be set forth in the followingdescription of specific apparatus embodying and utilizing our novelmethod. It is therefore to be understood that our method is applicableto other apparatus, and that we do not limit ourselves, in any way, tothe apparatus of the present application, as we may adopt various otherapparatus embodiments, utilizing the method, within the scope of theappended claims.

Referring to the drawings: Figure 1 is a longitudinal, sectional view,conventionalized, of one embodiment of our invention as applied topre-heatlng canned food.

Figure 2 is a fragmentary, sectional view of an alternative method ofmaking connection to the lower part of the can. Figure 3 is afragmentary view in section of a top electrode as applied to a closedcan.

Figure 4 is a view partl'y in section and partly in elevation of a canshowing side contact electrodes.

' Figure 5 is a plan view of an oval can indicating electrode contactarea.

Figure 6 is a diagrammatic sectional view showing the can of Figure 5positioned between two electrodes.

Figure 7 is a schematic sectional view of a preheating turntable.

And Figure 8 is a plan view/partly in section look ng-down on the top ofthe turntable illustrated in Figure 7.

At the present time cannery practice consists broadly in placing food incans which are fol'fiid from-tin plate; the latter being usually a thiniron sheet protected on both sides thereof by a ll film of pure tin. Thecans have many shapes,

but are usually formed with the side walls in the shape of a cylinder,the top and bottom being rolled or crimped in place toform an airtight,seal.

Inasmuch as the majority of canned foods are ,5 cooked during thepacking process, thecraw food is usually placed in the can and the canand its contained food are then pre-heated to definite temperatures todrive out gases and air contained therein, before closure. .The top isthen put on, m spun into place, and the cans are given final cooking.The removal oithe gases before the final cooking step prevents thecovers from being strained by expansion of gas. Sometimes, how= ever, asfor example, in the case of condensed 5 milk or canned beer, the coversare spun on and the can is then given a pasteurimng heating withoutpre-heating.

In prior practice it has been customary, in the pro-heating,pasteurizing or cooking steps;, to as conduct the can into steam boxeson conveyor belts, so that continuous progression may be obtained duringthe heating step. This necessitates rather large steam volumes toaccommodate the long length of conveyor belt so that the cans may remainin the box for the proper length of time. Furthermore, the live steamsup plied to these cabinetsv is continually escaping through theentrance and exit holes of the cabinet, and in order that evenpartialefiiciency may 30 be obtained the cabinets must be completely and ratherheavily insulated.

Our invention, broadly, comprises eliminating the steam cabinet eitherfor pre-heating, 'pas= teurizing or cooking and substituting thereforelectrical heating of the contents of the can by utilizing the tin plateside walls of the can itself as a resistance element, andpassingtherethrough electrical current of extremely high densities atlow voltages until the desired heat is developed in the contents 'of thecan. Our method is therefore not adapted to containers having insulatingwalls such as glass jars.

We are aware of the fact that it has previously been proposed to heatpackaged foods by passing an electrical current through the food itself;and we are also aware of the fact that it has previously been proposedto place the food in speciai containers, such as graphite cooking pots,"and pass a current through these containers'to heat '50 thefood,'thereafter transferring the heated food to the can. We have found,however, that such prior practices do not produce the advantages hereinto be set forth, as in many cases it is highly,v detrimental to the foodto pass a current as through it, and, again, the food itself may be sonon-conducting as to make such a procedure impossible. Furthermore, wedo not have to provide any special crucibles or cooking pots; we utilizeas a resistance element the identical container in which the food islater to be sold, and it never has to be removed from that containerafter heating. Consequently there is no chancefor the food, aftersterilization, pasteurization or cooking, to become contaminated.Furthermore,we havefound thatbyutilizingthis electrical method ofheating, temperatures can be very strictly controlled, there is a higheiiiciency v of energy conversion, and theheating may take place in arelatively short time and in a space which is relatively small comparedto the steam cabinets heretofore deemed necessary.

There are several means by which we apply current to tin cans, severalof which are'ilius ao trated' in the drawings to which-we will nowrefer.

In Figure 1 we have shown in a conventionalized manner a tin cancomprising the usual cylindrical side wall I, closed at the bottom bybottom disc 2 with the 'usual rolled, seam 3. The top of the can, notyet being closed, is provided with a rolled edge 4 which will laterenter into a top rolled seam similar to seam 3. We prefer to positionthe can in a depression 5 on a lower plate 301, which may well be acopper plate forming a portion of a traveling belt, or, as will later bedescribed, the bed plate of a turntable. Depres sion 5 is so out thatscentral boss I projects upwardly to contact the raised can bottom 2,thus affording a wide electrical contact overthe entire bottom of thecan.

The top of the can is contacted by a swinging electrode 8 hinged to aconductor bar 9, and

preferably provided with a flexible jumper id to do carry current aroundthe bearing. Top electrode 8 is preferably provided with a centralaperture il over the can to allow escape of gases from the contents l2of the can, and on its under surface is provided with a circular channelII.

shaped'to fit the rolled edge 4 of the top of the can. We prefer toplace considerable pressure between the top and bottom electrodes, andthis pressure may be supplied by a spring ll or, if desired, by makingelectrode! of suflicient weight to provide pressure by gravity alone, orboth. Base and conductor bar 9 are connected to the low voltagesecondary I! of a step-down transformer It, whose primary i1 isconnected to the alternating current mains in any convenient of the canand we have found in practice that I for a one-pound-tall can a currentof 400 amperes as at .1 volt applied for! minutes develops sumcient heatin the exterior walls to heat a can filled with water to the boilingpoint.- Other foods or mate-- rials contained in the can may take longeror I .shorter periods of applied heat. The cans then pass from thecooker.

often happens,' however, that cans are lacqueredon their inner surfacein order to better preserve the container walls from certain belt orturntable to theseiler' where the top is crimped on,'and thence to thecorrosive actions of the contained food. In this case, standard practiceis to thinly lacquer the cylinder l and the bottom 2 before the bottomis crimped to the cylinder. When the scam I is formed, we have foundthat under these circum- 5 stances a lacquer film may be includedbetween the material of bottom 2 and cylinder I, there creating a highresistance path. It is obvious that inasmuch as low voltage current isused that such resistance will develop excessive heat- 10 mg withconsequent loss of the seal at the seam, and .we have thereforeprovided, as shown in Figure 2, a different arrangement for the bottomof the can, where the recess I is filled with a good conductor, such asbrine it, for example, which 15 will contact the can above the seam 3.The thin lacquered seams never form a totally insulating joint, and theconductivityof the brine is suflicient to prevent heating of the seam asa large portion ofthe current is passed into the can go through thebrine contacting the side walls directly.

necessary within the can and an extremely high resistance is developed,I may prefer not to utilize 25 the top or bottom of the can for contactpoints, but to make contact directly to'the upper and lower portionsof'the side walls as shown in Figure 4. Here, lateral arms I! carrysubstantially semi-circular contacts, which may be moved radially towardthe axis of the can to clamp the can immediately below the top rollededge. Similarly, the bottom may be clamped by contact arms 2|, havingcontact electrodes 22 attached thereto in exactly the same manner as theupper set of electrodes. Inasmuch asthe contacting is done above andbelow the seam planes, it is obvious that a totally insulating seamcould be used on both top and bottom of the can,

irrespective of theconductivity of the top and 0 bottom seams. It shouldbe pointed out in this respect that the lateral seam 24 ofthe can, whichjoins the edges of theside walls so that the cylinder I may beformed, isnot across the path of the current, as the current flows parallel to thea seam and therefore this seam is never damaged. In clamping the cantightly with the lateral type of clamps'it is obvious that the seam 24may be positioned between two opposing electrodes so that the electrodescan contact the entire--oonbe omitted and channel i2 may be changed incontour to arecess-of the same shape as recess I on the bottomelectrode, there being also in this case-a projection I so that theentire top. of

w So far we, have shown our new invention as applied to"tall cans, thesecans being very satisfactory for heating because they provide a haveshown an example of this type of can in 'Figure 5 and Figure 8, theexample being the well known oval sardine can 23. In order to provide alonger pathfor the current we prefer to form a lower electrode IIsmallerthan the area of the is aisaaes bottom of the can but having thesame contour, and pomtion it so that all current paths from thiselectrode to top electrode 8 will be substan- 4 tially the same length.Thus the current travels for a considerable extent through the bottom ofthe can as well as the side walls, and this extra extent provides thedesired resistance. Furthermore, while in this case we have shown topelectrode l as appliedto the entire top of the can, it

is obvious that the top electrode 8 may be made the same shape and sizeas lower electrode 25.

In Figures '1 and 8 we have shown, greatly conventionalized andsimplified, a turntable on which the cans may be electrically heated. A

turntablebase 21 is mounted on a shaft 28, the latter being supported bybearing 29. Conductor bar 9 here is in the form of a ring concentric,with the periphery of theturntable, and upper electrodes 8 are hingedto this conductor bar as before recited. The bottom of the cans areplaced in depressions asdescribed in Figure '1. The cans are fed to theturntable from the conveyor line through entrance chute 30' by starwheel III and leave by exit chute 3|, the turn table rotating at a speedwhich will give the required heating between the time of entrance andexit. The conductor bar 9 and base 21 are energized from transformer l6,which in this case is mounted to rotate with the turntable so that thelow voltage secondary leads will not have to be brushed. Brush rings 32are mounted on insulating block 33, can'ied on shaft 28, and are contacted by stationary brushes 34 which lead to the mains through a switch36. Switch 36 is utilized to cut the current through the transformer atthe instant the cans enter and leave the turntable so that the primarycircuit may be broken when secondary contact across the can is madeor-broken by the movements of electrodes 8 actuated by lifting cam 31.Switch 3|, of course, may be automatically operated, and those skilledin the art will easily understand proper connections. The intermittentexcitation of the.

cans will, of course, lengthen somewhat the time the cans are on theturntable, but as the com nection and disconnection may be made rapidlythe time is not greatly prolonged. In order that heat may be conservedwe may prefer to cover the entire turntable with an insulating cover 38.

We have found that our system of can heating greatly reduces space incanning lines, re

duces heat losses, and provides an accuratelycontrollable heating foreither open or closed cans for pre-heating, pasteurizing or cooking. Wehave found that the final product is in all ways fully equal to steamheated products and in tained with steam boxes. Steam boxes-are con-'tinually leaking stefam and thissteam condenses on every objectsurrounding the packing lin'e, providing ideal conditions-for the growthof bac-' term and fungus. Everything is continually wet, also leading torust of machinery. The elimination of such leaking steam allows the sur-[I roundings and machinery to be dry, thus greatly reducing the chancesof contamination of food and prolonging the life of the equipment.

Another extremely important advantage of our process lies in the factthat we are able to attain cooking temperatures which cannot be attainedby the use of steam. For example, in packing sardines it-is highlydesirable that the cooking be carried on to the point that the layer offat directly under the skin is at least partially tried out. Atemperature sufficiently high to do this, however, cannot be attained insteam boxes, because it is not possible to apply steam to the cans underpressure because of leakage. It is also impractical to retort the opencans, and therefore it has heretofore not been possible to processsardines as sardines grilled in the can. For example, even when-steam isadmitted to a steam box under super-heated conditions, leakage preventsthe applied temperature; from rising over 210. Our process, however,will pro.- vide a sufliciently high temperature so that the sardines maybe fried or grilled in the can be- .fore the cover is placed upon it,and a superior product results. Other foods may be treated in the samemanner with high temperatures.

It is to be distinctly understood that our process applies to anyheating or the cans, whether open or closed, including cooking,pro-cooking, exhausting, processing, 'pasteurizing, sterilizing,blanching, concentrating foods or vegetables or liquids, frying,grilling or toasting, either wet or dry organicmaterials, and in thisregard our process is applicable to the heat treatment of any organicmaterial, wet or dry, whether or not it is being processed for human oranimal consumption. Our process is, of course, equally adaptable for theheat treatment of liquids, as

exemplified by condensed milk and beer.

It is also to be distinctly understood that our .process is fullyadapted for use in conjunction with containers formed of-materials otherthan tin plate. For example, certain novelty packs may be packaged andsold in special containers formed of thin walled metals such as, forexample,

While in tinned iron containers known to the trade as the passage ofsaid heating current.

2. The method of processing .relatively non- V conductive organicmaterial processed and sold in tinned iron containers known to the tradeas tin cans, having a side seam andan end seam, which comprises heatingsaid container when filled by applying a heating current to the walls ofsaid container across said end seam and parallel to said side seam, andproviding an auxiliary current path around said end seam during thepassage of said heating current.

conductive organic material processed and sold in tinned iron containersknown to the trade as tin cans, which comprises filling said containerswith said material, onveyingthe filled contain? ers over a predeterminedpath. applying a low .voltace heating current to top and bottom of said7 2,188,888 ,3. The method or p relatively non-- containers atapredetermined point in said path to heat the entire side walls of saidcontainer, maintaining said current until said material is processed,and removing said containers from the end of said path.

. O'I'I'O W. LANG.

HAROLD C. BETTE.

